Dispersants used to break up crude leaking from a ruptured Gulf of Mexico oil well are not likely to accumulate in seafood and affect humans, the US Food and Drug Administration said.

In a letter released Friday addressing concerns raised by a US lawmaker, the regulatory body said it was highly unlikely that the chemicals used to break up spilled crude into small particles would enter the food chain.

The "FDA has determined that the chemical dispersant currently used to combat the Deepwater Horizon... have a low potential for bioconcentration in seafood species," the agency said.

"Although seafood is exposed to the dispersant, the inherent properties of the dispersants minimize the possibility of their being present in food," the letter continued.